<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>js输出</title>
</head>
<body>
    <p id="demo">this is a paragraph.</p>
    <script>
        // window.alert(5+6);
        // alert("alert!");
        document.getElementById("demo").innerHTML="paragraph had changed."
        document.write(Date())
        console.log("双双最厉害啦！")
    </script>
</body>
</html>